Telephone-exchange system.



c. WQKECKLER. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR. 24. [EU- Patented July 2,1918.

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S A A NT cries/IT CHARLES w. KECKLEBI, OFYNEWARKVNEW JERSEY, nssreivonr0 wnsrnnnnnncrnrc COMPANY, INCORPORATED, or NEW YGRK, N. Y., ACORPORATION on NEW YORK.

To all whom it may concern: Be it known that'I, GHARLEs VV.;K.E0KLER, acitizen of the United States, residing at 'Newarlqin the county of Essexand State of New Jersey,- have invented certain new and usefulImprovements in Telephone-Exchange Systems, of which the following is afull, clear, concise, and exact dBSCIlPtlOII. This invention relates totelephone ex change systems, and more particularly to such systems ofthe centralene'rgy type,its object being to improve the service renderedby such systems. c In accordance with a feature of thisinventi on, a"link circuit employed for connecting'together telephone linesterminating at a central office is provided with meansfor automaticallyconnecting an operators tele-. phone set thereto upon connection of thelink circuit with a calling line.- Preferably the means employed is anelectromagnetic relay common to a plurality of link circuits.-

Inaccordance with another feature of this invention, means are providedfor the link circuits by which it is impossible to connect theoperatorstelephone set to more than onelink circuit at a time;

'This invention is illustrated in the accompanying drawing in whichallapp'aratus is in its normal'p'osition with the 'operatorstelephoneset disconnected'from-the link circuits; 4

In the-drawing there are shown two ordinarytelephone lines A and Bextending from subscribers stations and terrninating at a central officewhere there are locateda plurality' of link-circuits G and Dforinterconnecting the telephone lines. Only so much of the linkcircuits as is necessary "for a proper understanding of this inventionis shown. i 1 I Thegconnection of'an operators telephone .set with thelink circuitiscontrolled by a relay 5=common to the link circuits. Thisrelay 5 is in series witha polarized relay 6, across a Wheatstone bridgehaving three arms common to the li'nkcircuits, the fourth arm beingprovided in the separate link circuits. The arms common to' the 'linkcincuitsare 7, 8 and 9'; The resistances of these arms are so proportionedthat, when none of the link circuits are inuse, there isfa flow ofcurrent'from battery through the contact of key 11 to a point 12 whereit divides, a portion going through resistance arm 7 to a I eSpecificationof Letters Patent.

App1icati0nfi1edApri124, 1917. Serial No. 164,172.

TELEPHONE-EXCHANGE sYsrnivr, 7

Patented July 2, 1918.

point 18, and another portion going through resistancearnl 8 and thewindings of polarized relay 6 and relay 5 to the point 13 and thencethrough resistance'arm 9' and ground. The polarized relay 6is so poledthat-it does not attract its'armature when traversed by current flowingin the direction just traced.

Relay 5, however, is operated,- maintaining the operators telephone setdisconnected from the link circuits. When the answering end of any-linkcircuit, as C, is connected with a telephone line, the resistance 10C isconnected with the Wheatstone bridge and forms the fourth arm thereof.The bridge is now balanced and relay 5 releases its armatures,connecting the operators telephone set with the link circuit. Should theanswering ends of two link circuits be connected with two telephonelines simultaneously, resistances l0- C and lO-D will be connected inparallel to form the fourth arm of the bridge, and'when so connected thebridge will be unbalanced. Relay 5',will, therefore, be operated,disconnecting the operators telephone set from bothlink-circuits. Thedirection of flow ofcurrentthro'u h relays 5 and 6 will be such thatpolarize relay 6 attracts its armature causing the operation of a lamp14, indicating to the operator that the answering ends of two linkcircuits have been connected with two telephone-lines, while thecalling'end of neither link circuit is engaged. f "y Operation: Assumingthat the subscriber of telephone line A has initiated a call in theusual manner, the operator in answering inserts answering plug 25 of thecord circuit G into line jack 26, whereupon answering sleeve relay27,-vand cutoff relay 28 are operated. The operation of relay 27'connects answering supervisory relay 29 to the talking strands of thecordcircuit, which is thereupon operated to prevent the lightingarethereupon operateda The subscriber of telephone line B may besignaled" in any Well-known manner. The operation of relay 'ssui'scoimeets"-tlie' conini'oii" circuit leads 35and 36 frcnrthe talking stiaiidsof cord circuit C, and also disconnects resistance 10 from theVVheatstone bridge, thereby destroying the balance, and permitting the Vi l The eii'ei giz'ation of relay 5 disconnectsthe operators telephoneset from the common loads 35 and 36. The operation of relay 33alsoconnectsica'lli1ig .-superyisory relay 89 to the talking strands of cordcircuit C, and causes the operation of, calling supervisory. lamp 40.In'gresponse; ,to t he operation of the call bell at station B, thesubscriber removes the receiver-from ,the switchhook,therebycausing'gthe operation of the ca li g s u r relay}? to extinguish thecalling supervisory lamp-40. At the. conclnsi on' of the conyersationthe restoration of the receivers touthe switchhooks causes thedenergi-zation of thegsupervisory relays 29*and 39,: Where'- uponihelamps 3 0 and 40 are lighted to furniish disconnect "signals. 7 Theoperator may vno;remove theplugs from the jacks, re storing li ll'apparatus to normal.

Should the operator have inserted the a11sWering p*lu-g25 of cordcircuit D int-o tl ej ack of another calling line before the callingplug 31- of the cord circuit C was insertedinto the jack 32 of'line D,the resistance 10+Dwould be connected in parallel ryith the resistance:10'C, whereby the resistance-of the fourth arm' of the \Vheatstonebridge circuit would be reduced, destroying the balances Current wouldthen flow frorn -battery through the contact of key ll, ,bridge arm ;7and the, windings of relays ti andfi'e and the bridge arm 8 in paralleltherewith and the resistances, 10-C in parallel 'to ground. 'IZ hecurrent in this path operates relay -5,,thereby disconnecting the operatorstelephoneyset from the common leads 35 and 36. Polarized relay .6 isalso operated, causing the lighting of'the lam p -ld, which is a signalto the operator that theanswering-endsof two cord ,circ uitsha've beenconnected With two telephone lines, Whilethe calling end of each'ofthe'cord circuits is not in use. VV'hat isclai nedis: I a telephoneexchange system.comprising telephone lines, a plurality of cord rcuits,an operators telephone set, and i a normallyenergized relay "common tothe cord circuits denergized uponthe connection 'of o ne end of one of;the 'cord circuits with one telephone line ;to connect there- Withgthioprators telephone set and energized n'ponthe connection ofthc othervend of the cord icircuit i ithanother telephone "to disconnect. the'opera'tors telephone 2; 'A t'lephon"exchangefsysteni dee en"\iiitlr'oii'e er the telephone lines to complete-,-

the fourth arm' of the bridge circuit, and a stritc'hi'ng'device in thebridge responsive to the completion of tvhe fourth arm thereof toconnect the operators telephone set with the engaged link circuit.

3. A, telephone exchange systenr comprising telephone lines, a pluralityof linlcycircuit's, an, operators telephone set,- a VVheatstone-bridgecircuit common tothe link circuits,, mfeans actuated uponconnection. ofone of the link circuits with one of thelines to; alter the electricalcondition of the Wheatstone bridge-circuit, and a switcl'ring device in'thebridge:responsive to the altered condition thereof to, connect theoperators telephone set with the engaged link circuit.

4. A telephone exchange system compris in-g telephone lines, a pluralityof link cir-- cuits, an operators telephone set, a VVheatstone bridgecircuit having three arms con i'n'on to the circuits, a resistance ineach link circuitadapted to form the fourth arm of the bridge, a relayperating upon connection of one of the link circuits with one of thetelephone lines to connect the associated resistance with the bridge,and a relayin the bridge responsive to the connection of the resistancewith the bridge to connect theoperators telephone set With the engagedlink circuit.

5. A telephone exchange system comprisingtelephone lines, a plurality oflink cir- Cults including talking conductors forinterconnecting" thelines, an operatofls telephone set, circi'iitleads common to the linkcircuits and normally connected to the talking conductors thereof, andmeans common to the link circuits for connecting the operators telephoneset to the common circuit leads.

or '6. A telephone exchange system} comprisi-ngtelephone lines, aplurality of link circuits including talking conductors forinte'rconnecting'the lines, .an operatofls telephone set, circuit leadscommon to the link ing conductors thereof, means coiirmon =to tlie' link:circuits for connecting the operetors telephone set 'to the commoncircuit leads, and means associated with an cn gaged link circuit fordisconnecting the common circuit leads from the vtalking con-.

thereto, c a relay common to the link circuits responsive to theconnection of one end of one of the link circuits with a telephone lineto connect the operators telephone set with the common circuit leads,and a relay responsive to the connection of the other end of the engagedlink circuit with another telephone line to disconnect the commoncircuit leads from the engaged link circuit.

9. A telephone exchange system comprising telephone lines, a pluralityof link circuits, an operators telephone set, a Wheatstone bridgecircuit common to-the link circuits, means actuated upon connection ofone end of one of the link circuits with one of the telephone lines toalter the electrical condition of the Wheatstone bridge circuit, aswitching device in the bridge responsive to the altered conditionthereof to connect the operators telephone set with the engaged linkcircuit, and means responsive to the connection of the other end of theengaged link circuit with another telephone line to restore theVVheatstone bridge circuit to normal condition to thereby disconnect theoperators telephone set from the engaged link circuit.

10. A telephone exchange system comprisciated resistance with thebridge, a relay in the bridge responsive to the connection of theresistance with the bridge to connect the operators telephone set withthe engaged link circuit, and a relay associated with the second linkcircuit operating upon connection thereof with a second telephone lineto connect its associated resistance with the bridge and in parallelwith the resistance of the first link circuit, the relay in the bridgebeing responsive 'to such connection to disconnect the operatorstelephone set from the engaged link circuits.

11. A telephone exchange system comprising telephone lines, a pluralityof link circuits, an operators telephone set, a'Wheatstone bridgecircuit having three arms common to the link circuits, a fourth arm forthe bridge connected therewith upon connection of one of the linkcircuits with one of the telephone lines, and a switching device in thebridge responsive to the connection of the fourth arm to the bridge toconnect the operators telephone set with the engaged link circuit.

12. A telephone exchange system comprising telephone lines, a pluralityof link cir cuits, an operators telephone set, a Vheatstone bridgecircuit having three arms common to the link circuits, a fourth arm forthe bridge connected therewith upon connection of one end of one of thelink circuits with one of the telephone lines, a switching device in thebridge responsive to the connection of the fourth arm of the bridge toconnect the operators telephone set with the engaged link circuit, andmeans responsive to the connection of the other end of the engaged linkcircuit with another telephone line to disconnect the fourth arm fromthe bridge. i

'In witness whereof, I hereunto subscribe my name this 20th day ofApril, A. D. 1917.

CHARLES W. KE OKLER.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents.

Washington, D. G.

